This invention relates to an image processing apparatus and method and an information providing medium, and more particularly to an image processing apparatus and method and an information providing medium by which a three-dimensional model can be plotted efficiently and accurately.
Various methods of plotting a three-dimensional model by group approximation data CG (Computer Graphics) have conventionally been developed and include a lighting process or rendering process proposed by Foly. van Dam., xe2x80x9cComputer Graphics, principles and practicexe2x80x9d, Addition Wesley Publication, image-based rendering proposed by Paul E. Debevec et al., xe2x80x9cModeling and Rendering Architecture from Photographs: A hybrid geometry and image-based approachxe2x80x9d, Proceedings of SIGGRAPH 96, pp.11-20 wherein a plurality of paste images to a general shape are prepared and a paste image is switched and plotted in accordance with a viewpoint direction so that detailed plotting of a high quality can be executed, a method proposed by Huges Hoppe, xe2x80x9cMesh Optimizationxe2x80x9d, Proceedings of Siggraph 93, pp19-26 wherein shape data of different particularity degrees are produced from the most particular shape of a three-dimensional model and a shape of a model is approximated, and texture mapping proposed by Foly. van Dam., xe2x80x9cComputer Graphics, principles and practicexe2x80x9d, pp.827-828, Addison Wesley Publication, 1996 wherein textures having different resolutions are prepared in advance and a texture of a resolution suitable for a size of a three-dimensional model on a display is pasted to a surface of the three-dimensional model.
Further, in recent years, development of a plotting processing method for plotting an existing object with an increasing accuracy has been proceeded. For example, a method of changing a plotting processing method in response to a shape of a model to be plotted has been proposed. According to the method, from among displacement mapping by which a concave and convex configuration of a surface of a model can be plotted with a high degree of accuracy, flat shading which is suitable to paint a surface of a model with a single color but cannot plot a concave and convex configuration accurately and bump mapping by which a concave and convex configuration can be plotted with an intermediate degree of accuracy between those by the displacement mapping and the flat shading, an optimum plotting processing method is selected in response to a shape of a portion of a model to be plotted. Details of the method are disclosed in Barry G. Becker, xe2x80x9cSmooth Transitions between Bump Rendering Algorithmxe2x80x9d, Proceedings of Siggraph 93, pp.183-190.
Another method has been proposed wherein the color of a surface of an object (the color is hereinafter referred to as surface color) which varies depending upon the position of a viewpoint or the position of a light source for lighting an object is measured in advance and surface color data measured are approximated in response to the position of a viewpoint or the position of a light source when a model is plotted. If the direction V in which a user observes an object (or the direction in which a camera for picking up an image of the object is directed) (the direction is hereinafter referred to as viewpoint direction) is set, for example, as seen in FIG. 17A, to a direction V1 perpendicular to the plane of the figure and the direction L in which a light source for lighting the object is directed (the direction is hereinafter referred to as light source direction) is set, for example, to a direction light source direction L1 in which the object is lighted obliquely from left above, then a highlight is formed at a left upper portion of the object.
Since the surface color of an object varies finely stepwise (gradually) in the proximity of a highlight, with the proposed plotting processing method, the portion at and around the position at which the highlight is present is approximated comparatively finely while the remaining portion is approximated comparatively roughly. For example, when an object is modeled with polygons of a wire frame display as seen in FIG. 17B, a portion of the object at which a highlight is present is displayed with more dense wire frames and approximated more accurately than the other portion of the object. Therefore, an object can be plotted more accurately than where it is approximated alternatively such that it is displayed with uniform wire frames as seen in FIG. 18.
FIG. 19A shows an image of the object when the viewpoint direction V is maintained at the direction V1 perpendicular to the plane of FIG. 19 whereas the light source direction L is changed from the light source direction L1 to another light source direction L2, and FIG. 19B shows a model corresponding to the image. In this instance, the model is approximated in accordance with a highlight formed on the left side of the object.
It is to be noted that a method of optimizing the reflection characteristic of a point on the surface of an object in such an instance to produce image data of the surface color (the data are hereinafter referred to as surface color data) is proposed in the model of Lambert, the model of Phong or the model of Cook-Torrance, and is disclosed in Andrew S. Glassner, xe2x80x9cPrinciples of Digital Image Synthesisxe2x80x9d, Morgan Kaufmann Publication.
While methods of plotting a model with a high degree of accuracy are being studied in this manner, since the plotting processing method described above produces a model with the surface color and the shape of the model optimized separately from each other, it after all has a subject to be solved in that a model of an existing object cannot be plotted accurately even at present.
Further, since optimization of data is involved, an apparatus which executes a plotting process has a subject to be solved in that it cannot execute a plotting process efficiently.
It is an object of the present invention to provide an image processing apparatus and method and an information providing medium by which a model can be plotted efficiently and accurately.
In order to attain the objects described above, according to a first aspect of the present invention, there is provided an image processing apparatus for producing a model of an object, including inputting means for inputting model data of the object having shape data of the object, and control means for allocating an optimum process to each of a plurality of regions which compose the model data.
According to a second aspect of the present invention, there is provided an image processing apparatus for performing display control of a model of an object, including inputting means for inputting model data with which a process is allocated to each of a plurality of regions of the model of the object, and plotting means for selecting a process allocated to each of the regions of the model data and plotting the region to which the process is allocated based on the selected process.
According to a third aspect of the present invention, there is provided an image processing method for producing a model of an object, including an inputting step of inputting model data of the object having shape data of the object, and a control step of allocating an optimum process to each of a plurality of regions which compose the model data.
According to a fourth aspect of the present invention, there is provided an image processing method for performing display control of a model of an object, including an inputting step of inputting model data with which a process is allocated to each of a plurality of regions of the model of the object, and a plotting step of selecting a process allocated to each of the regions of the model data and plotting the region to which the process is allocated based on the selected process.
According to a fifth aspect of the present invention, there is provided an information providing medium which provides a program to an information processing apparatus which includes a control apparatus which can execute a program, the program having an inputting command for inputting model data of the object having shape data of the object, and a control command for allocating an optimum process to each of a plurality of regions which compose the model data.
According to a sixth aspect of the present invention, there is provided an information providing medium which provides a program to an information processing apparatus which includes a control apparatus which can execute a program, the program having an inputting command for inputting model data with which a process is allocated to each of a plurality of regions of the model of the object, and a plotting command for selecting a process allocated to each of the regions of the model data and plotting the region to which the process is allocated based on the selected process.
According to a seventh aspect of the present invention, there is provided an information providing medium for providing image data to an information processing apparatus which can read in data, the image data being produced by an inputting step of inputting model data of the object including shape data of the object, and a control step of allocating an optimum process to each of a plurality of regions which compose the model data.
With the image processing apparatus and methods and information providing media, model data of an object including shape data of the object and surface color data of the object which correspond to each other are produced and optimized based on a plotting condition for plotting a model, and a model of the object is plotted based on the optimized model data. Consequently, the model of the object can be plotted efficiently and accurately.
The above and other objects, features and advantages of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings in which like parts or elements denoted by like reference symbols.